1. Field of the Invention
This invention relates to production of .alpha.-olefin polymers, and more particularly it relates to a process for producing highly crystalline .alpha.-olefin polymers having a good particle form, with a high yield, by the use of a preliminarily activated catalyst which is suitable for polymerization of .alpha.-olefins, particularly gas phase polymerization, and further, as a modification of gas phase polymerization, a combination of gas phase polymerization with slurry of bulk polymerization.
2. Description of the Prior Art
The inventors of the present application have developed processes for polymerizing .alpha.-olefins including ethylene, by the use of catalysts comprising a combination of an organoaluminum, etc. with a solid product (which will be hereinafter referred to as solid catalyst component) obtained by having a transition metal compound supported on a solid product (I) obtained by reacting a trivalent metal halide with a divalent metal compound, in the following various reaction manners.
For examples, the following processes have been proposed:
(1) a process wherein a transition metal compound is reacted with the above-mentioned solid product (I) in the presence of an aromatic compound (Japanese patent publication Nos. 13,609/1972 and 16,782/1974);
(2) a process wherein the above-mentioned solid product (I) is reacted with a polysiloxane or an electron donor, and thereafter with a transition metal compound (Japanese patent publication No. 13,827/1977; Japanese patent application laid-open No. 61,283/1979);
(3) a process wherein a polysiloxane or an electron donor and a transition metal compound are added at the same time or a complex of them is added to the above-mentioned solid product (I), to effect reaction (Japanese patent application ) laid-open Nos. 116,078/1979, 113,687/1979 and 124,091/1979);
(4) a process wherein either one or both of at least one kind of electron donors and at least one kind of electron acceptors are reacted with the above-mentioned solid product (I), in a plurality of divided portions (Japanese patent application No. 101,960/1978);
(5) a process wherein at least one kind of electron donors and at least one kind of electron acceptors are reacted with the above-mentioned solid product (I), and at that time, TiCl.sub.4 is employed as the electron acceptor at least once, and further the resulting solid catalyst component, an organoaluminum compound and an electron donor are combined together (Japanese patent application No. 106,797/1978);
(6) a process wherein at least one kind of electron donors and at least one kind of electron acceptors are reacted with the above-mentioned solid product (I), and at that time, TiCl.sub.4 is employed as the electron acceptor at least once, and then a combination of the resulting solid catalyst component with an organoaluminum compound, an .alpha.-olefin and an electron donor is subjected to a polymerization treatment to prepare a preliminarily activated catalyst for .alpha.-olefin polymerization (Japanese patent application No. 148,1978); and
(7) a process wherein various additives such as titanium alkoxides, silicone oils, polyethylene glycol dialkyl ethers, other electron donors, etc. are added at the time of polymerization (Japanese patent publication Nos. 13,609/1972, 13,772/1972). The inventions of these processes (1) to (7) will be hereinafter referred to as prior inventions.
In case where these prior inventions are applied to slurry polymerization or bulk polymerization, various advantages are brought about such that polymer yield per unit weight of catalyst component is very high; crystallinity of polymers of .alpha.-olefins such as propylene is high; particle form of polymers is good; further in the case of the inventions of the processes (5) and (6), it is possible to control the molecular weight distribution into a narrower range; etc. However, the .alpha.-olefin polymers obtained according to the prior inventions of the present inventors had lower rigidities; hence they have been unsuitable for the application fields where higher rigidities have been required.
Thus, the present inventors have made studies for enhancing the rigidity of .alpha.-olefin polymers, and as a result have found a process for improving the rigidity by the use of a preliminarily activated catalyst (abbreviated hereinafter to "preactivated catalyst") obtained by combining an organoaluminum compound, an electron donor and an .alpha.-olefin with a solid catalyst component obtained by employing an organomagnesium compound as one of the substances to be reacted with the above-mentioned solid product.